IL-4 regulates neutrophilic pulmonary inflammation in a mouse model of bronchial asthma

Neutrophilic pulmonary inflammation in asthmatics substantially exacerbates the severity of the disease leading to resistance to conventional corticosteroid therapy. Many studies established the involvement of Th1- and Th17-cells and cytokines produced by them (IFNg, IL-17A, IL-17F etc.) in neutrophilic pulmonary inflammation. Recent studies revealed that IL-4 - a Th2-cytokine regulates neutrophil effector functions and migration. It was showed that IL-4 substantially reduces neutrophilic inflammation of the skin in a mouse model of cutaneous bacterial infection and blood neutrophilia in a mouse model systemic bacterial infection. However, there are no data available regarding the influence of IL-4 on non-infectious pulmonary inflammation. In the current study we investigated the effects of IL-4 in a previously developed mouse model of neutrophilic bronchial asthma. We showed that systemic administration of IL-4 significantly restricts neutrophilic inflammation of the respiratory tract probably through the suppression of Th1-/Th17-immune responses and downregulation of CXCR2. Additionally, pulmonary neutrophilic inflammation could be alleviated by IL-4-dependant polarization of N2 neutrophils and M2 macrophages, expressing anti-inflammatory TGFβ. Considering these, IL-4 might be used for reduction of exaggerated pulmonary neutrophilic inflammation and overcoming corticosteroid insensitivity of asthma patients.

Saturable absorber: transparent glass-ceramics based on a mixture of Co:β-Zn2SiO4 and Co:ZnO nanocrystals

We report on the development of novel saturable absorbers for erbium lasers based on transparent glass-ceramics (GCs) containing a mixture of cobalt-doped β-willemite, Co²⁺:β-Zn₂SiO₄, and zinc oxide, Co²⁺:ZnO, nanosized (10-14 nm) crystals. The structure of the parent glass and GCs is studied by x-ray diffraction, differential scanning calorimetry, transmission electron microscopy, and Raman spectroscopy. Variations of absorption spectra with heat-treatment reveal that Co²⁺ ions from the parent glass enter the crystals of ZnO and β-willemite. GCs are characterized by a broad absorption band due to the A₂4(F4)→T₁4(F4) transition of Co²⁺ ions in tetrahedral sites spanning up to ∼1.74  μm, relatively low saturation fluence, F_S=0.75  J/cm² at 1.54 μm, short recovery time, τ=830  ns, and high laser damage threshold, ∼14  J/cm². By using the developed GCs in a diode-side-pumped Er, Yb:glass laser, 0.77 mJ/45 ns pulses are generated.

Passive Q-switching of a Tm,Ho:KLu(WO4)2 microchip laser by a Cr:ZnS saturable absorber

A diode-pumped Tm,Ho:KLu(WO₄)₂ microchip laser passively Q-switched with a Cr:ZnS saturable absorber generated an average output power of 131 mW at 2063.6 nm with a slope efficiency of 11% and a Q-switching conversion efficiency of 58%. The pulse characteristics were 14  ns/9  μJ at a pulse repetition frequency of 14.5 kHz. With higher modulation depth of the saturable absorber, 9  ns/10.4  μJ/8.2  kHz pulses were generated at 2061.1 nm, corresponding to a record peak power extracted from a passively Q-switched Tm,Ho laser of 1.15 kW. A theoretical model is presented, predicting the pulse energy and duration. The simulations are in good agreement with the experimental results.

Dispersion and anisotropy of thermo-optic coefficients in tetragonal GdVO(4) and YVO(4) laser host crystals: erratum

We addressed errors found in our measurements of thermo-optic coefficients and thermal coefficients of the optical path (TCOP) in tetragonal vanadates, YVO(4) and GdVO(4) [Appl. Opt.52, 698 (2013)]. Modified thermo-optic dispersion formulas are presented for these laser host crystals.

Thermal lens study in diode pumped Ng- and Np-cut Nd:KGd(WO4)2 laser crystals

A comparative study of thermal lensing effect in diode laser pumped Ng- and Np-cut Nd:KGd(WO4)2 (KGW) laser crystals was performed for laser emission polarized along the principle refractive axis, Nm. The thermal lens in the Ng-cut Nd: KGW was found to be weakly astigmatic with a positive refractive power for both the Nm- and Np-directions. For Np -cut Nd:KGW, strong astigmatism was observed and the refractive powers in the Ng- and Nm-directions had opposing signs. The degree of astigmatism was found to be considerably weaker for the Ng-cut Nd:KGW in comparison with the Np-cut one: 0.35 dptr/(W/cm2) and 2.85 dptr/(W/cm2), respectively. The ratio of the thermal lens refractive powers in the planes parallel and perpendicular to the laser emission polarisation were measured as +1.4 and -0.425 for Ng- and Np-cut Nd:KGW respectively.

Yb3+-doped YVO4 crystal for efficient Kerr-lens mode locking in solid-state lasers

We report the first demonstration, to our knowledge, of soft-aperture Kerr-lens mode locking in a diode-pumped femtosecond Yb3+:YVO4 laser. Near-transform-limited pulses as short as 61 fs are generated around a center wavelength of 1050 nm with an output power of 54 mW and a pulse repetition frequency of 104.5 MHz. This is, to our knowledge, the shortest pulse generated directly from an Yb laser having a crystalline host material. The femtosecond operation has a mode-locking threshold at an absorbed pump power of 190 mW. The nonlinear refractive indexes of the Yb3+:YVO4 crystal have been measured to be 19 x 10(-16) cm2/W and 15 x 10(-16) cm2/W for the sigma and pi polarizations, respectively, at 1080 nm.

Saturable Absorber Cr(4)+:(Sr, Ca)Gd(4)(SiO(4))(3)O Crystals as Q Switches for a Diode-Pumped Nd(3)+:KGd(WO(4))(2) Laser

Passive Q switching of a diode-pumped Nd(3+):KGd(WO(4))(2) laser is demonstrated by use of Cr(4+):SrGd(4)(SiO(4))(3)O and Cr(4+):CaGd(4)(SiO(4))(3)O crystals as saturable absorbers. An average output power of 40 mW was obtained with a pulse repetition rate of ~0.4 MHz.

Cobalt-doped transparent glass ceramic as a saturable absorber q switch for erbium:glass lasers

A new saturable absorber Q switch for 1.54-mum Er:glass lasers is presented. The saturable absorber is a transparent glass ceramic that contains magnesium-aluminum spinel nanocrystallites doped with tetrahedrally coordinated Co(2+) ions. We obtained Q-switched pulses of up to 5.5 mJ in energy and 80 ns in duration at 1.54 mum. The relaxation time of (4)A(2) ?(4)T(1)((4)F) transition bleaching was measured to be (450 ? 150) ns. Ground-state and excited-state absorption cross sections at 1.54-mum wavelength were estimated to be (3.2 ? 0.4) x 10(-19) cm(2) and (5.0 ? 0.6) x 10(-20) cm(2), respectively.

Glass doped with PbS quantum dots for passive Q switching of a 1.54- microm laser

By using a PbS-doped phosphate glass as an intracavity saturable absorber, we achieved passive Q switching of a 1.54-microm Er:Yb:glass laser. We obtained Q-switched pulses with 110-ns duration and 0.2-mJ energy. The saturation intensity at 1.54 microm was estimated to be approximately 60 kW/cm(2).

Saturable absorber Co2+:MgAl2O4 crystal for Q switching of 1.34-microm Nd3+:YAlO 3 and 1.54-microm Er3+:glass Lasers

Saturable-absorber Q switching of a neodymium-doped YAlO(3) laser at 1.34 microm and an erbium-doped glass laser at 1.54 microm with a Co(2+):MgAl(2)O(4) crystal was demonstrated. Q-switched 1.34-microm pulses of 19-mJ energy and 60-ns duration and Q-switched 1.54-microm pulses of 2.7-mJ energy and 75-ns width were obtained. The ground-state absorption cross sections of the Co(2+):MgAl(2)O(4) crystal were estimated to be (2.8 +/- 0.4) x 10(-19) and (3.5 +/- 0.6) x 10(-19) cm(2) at 1.34 and 1.54 microm, respectively. The (4)T(1)((4)F)-->(4)A(2) relaxation time of the Co(2+) ion in the MgAl(2)O(4) crystal was measured to be approximately 350 ns.

Chromium-doped forsterite as a solid-state saturable absorber

Saturation of near-infrared absorption in Mg(2)SiO(4):Cr is observed, and the absorption cross section at 1.08 microm is estimated to be sigma(alpha) = (2.3 +/- 0.3) x 10(-18) cm(2). Q switching and passive mode locking of a Nd:YAG laser have been realized with a Mg(2)SiO(4):Cr saturable absorber.